Normal cartilage surface is a smooth surface without fracture or defects. Because the cartilage is a tissue without vascular, nervous and lymphatic system, the mature cartilage cells have limited repair capability to the damage caused by disease or injury (Mahmoudifar N, Doran P M. Tissue engineering of human cartilage and osteochondral composites using recirculation bioreactors. Biomaterials. 2005;26(34):7012-24). In addition, as lacking nervous tissue, the damage at early stage is not noticed. Because of lacking blood vessels, nutrients and progenitor cells in the blood cannot reach to the damaged area of the cartilage; self repair capability of the cartilage is limited.
The cell density of the tissue is very low; therefore, the damaged part of the cartilage cannot be repaired by the cell in time. The repair capability of the cartilage and that of bone are different, the latter has wider blood vessel distribution, providing sufficient blood nutrients and stem cells, and therefore a considerable degree of damage can be repaired (Huey D J, Hu J C, Athanasiou K A. Unlike bone, cartilage regeneration remains elusive. Science. 2012;338(6109):917-21).
Cartilage relies on synovial fluid infiltration to meet their nutrient needs. The lack of cell and related repair factors makes that even a small area of cartilage damage cannot be repaired successfully (K. A. Athanasiou EMD, J. C. Hu, Synth. Lect. Tissue Eng. 1, 1 2009). Articular cartilage damages are mostly caused by the joint trauma, abnormal joint loading or degenerative joint disease.
In the most severe situation of joint damage, patients cannot endure the pain to seriously affects their daily lives; so that osteotomy and artificial joint replacement are needed. Because cartilage is an extremely slow self repair tissue, a small area of joint damage in the condition of losing the normal physiological function of cartilage require to take other treatments in order to achieve relieving discomfort or cartilage repair purposes. For example, the treatment methods are injection treatment, drilling, autologous osteochondral transplantation and autologous chondrocyte transplantation.
Autologous osteochondral transplantation is a one-time surgery. The cartilage region of the unstressed joint area, together with subchondral bone is simultaneously removed and transplanted to the defect area. The disadvantage of the surgery is that the donation area lacks cartilage, and it is difficult to perform when the damaged area is larger than 4 cm2 (Hunziker E B. Articular cartilage repair: basic science and clinical progress. A review of the current status and prospects. Osteoarthritis Cartilage. 2002;10(6):432-63). Furthermore, the transplanted cartilage may not be perfectly integrated into the defect area.
The autologous chondrocyte transplantation requires two surgeries. In the first surgery, chondrocytes isolated from cartilage tissue removed from patient's unstressed healthy cartilage are amplified in vitro to operate the second surgery (Brittberg M, Lindahl A, Nilsson A, Ohlsson C, Isaksson O, Peterson L. Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation. N Engl J Med. 1994;331(14):889-95) in which the chondrocytes are collected and injected into the defect area, and is covered by the periosteum. The disadvantages of the transplantation are its complex process, and in the in vitro amplification process, the cartilage may lose its original morphology. Furthermore, the cellular fluid may also be exposed during the treatment of the outer periosteal suture (Mobasheri A, Csaki C, Clutterbuck A L, Rahmanzadeh M, Shakibaei M. Mesenchymal stem cells in connective tissue engineering and regenerative medicine: applications in cartilage repair and osteoarthritis therapy. Histol Histopathol. 2009;24(3):347-66).
Given from above, there lacks an ideal treatment for joint injuries. The autologous chondrocyte transplantation is currently popular therapy. However, healthy cartilage has to be removed from the patient's body as a result of lacking cartilage in donation area. Therefore the inventor uses tissue engineering methods for culturing tissues having cartilage characteristics from patient's autologous mesenchymal stem cells to facilitate cartilage transplantation.